1899] THE STUDY OF NATURAL HISTORY 441 



organic architecture, a general view of the certainties and possibilities 

 of blood-relationship among animals, a realisation of what the word 

 " organisation " means, and one criterion which will keep both teaching 

 and learning sane and interesting is the old criterion of natural 

 history. We must ask, Does this anatomical detail help us to a deeper 

 and clearer insight into the real life as it is lived in nature ? 



There are other criteria, which I do not propose now to discuss, 

 such as the rather dangerous criterion of practical utility, and what 

 may be called the biological criterion which asks whether this or that 

 piece of research or knowledge will help towards an understanding of 

 the big generalisations of the subject. 



The Second Question — How does this Act ? 



But close upon the first question — What is this ? there rises a 

 second — -How does this act ? It is equally natural and necessary, and 

 throughout the progressive periods in the history of biology the two 

 questions have never been far apart. They have evolved together, 

 especially during this wonderful century, prompting one another to a 

 more and more penetrating inquisitiveness. The key-word of the one 

 is structure or organ isation, of the other function or activity. The 

 creature which our first question killed and picked to pieces has to be put 

 together asain and made to work. What does it do ? how does it do 

 it ? how does it go ? how does it keep agoing ? how does it set other 

 creatures like itself agoing ? how long can it go ? how does it cease 

 from soino- ? In other words, how does the organism feel and move ? 

 how does it grow and multiply ? how does it waste, recover itself, and 

 finally, in most cases, die ? Above all, what is the secret of its 

 activity and of its power of effective response to the order of nature ? 

 These are some of the physiological questions which recall Clerk Maxwell's 

 boyish question — What is the go of this — the particular go of this ? 



We brush aside the old answers which speak of vital spirits and 

 vital force, of conflicting temperaments and principles of life, not for- 

 getting that we must sometime rehabilitate the truth which is in these 

 verbalisms ; we analyse the workings of the different organs which 

 co-operate in the life of the whole, such as the beating heart and the 

 digesting stomach ; we pass beneath this to study the tissues that build 

 up the organs — the contracting muscles, the controlling nerves, the 

 secreting glands ; we inquire yet more deeply into the waxing and 

 waning of the cells and the complex chemical changes which occur in 

 these ; and we find that our second question is as unending as the 

 first. 



Here and there we make clear a chain of events, a procession 

 of causes ; we discover the hidden uses of various parts ; we begin 

 to understand certain corners of the internal economy ; but to 

 counteract any feeling of self-satisfaction we have simply to watch 



